A series of MnOx/TiO2 catalysts were prepared by ultrasonic impregnation, traditional impregnation and sol-gel methods. Their properties were studied by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface measurement, high-resolution transmission electron microscope (HRTEM), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature programmed reduction(TPR) techniques and their catalytic performance for the selective catalytic reduction of NO with NH3(NH3-SCR)was investigated. It is found that the use of ultrasonic in the solution impregnation for preparing MnOx/TiO2 catalysts has significant effect on the dispersion behavior and surface acid property of manganese oxide on TiO2 as well as the catalytic activity. MnOx/TiO2catalysts prepared by UI (ultrasonic impregnation) method exhibits higher catalytic activity; especially at temperature below 120℃. NO conversion rate at 100℃ is about 90%. The characterization results indicate that the catalyst shows larger specific BET surface area; Ti and Mn have strong interaction; there is a significant amount of Lewis acidity and high concentration of Mn atom as well as the formation of abundant NH2 on the surface.